In current optical network transport equipment, each line card has multiple interfaces. Each interface can be connected to different clients on the ingress side. The transport equipment has the capability of transporting client traffic streams that have been generated using different clock domains. The transport equipment supports a single system reference clock and the egress clients are re-synchronized by a single clock.
Since the transport equipment has a single system reference clock, whenever the transport equipment receives two or more traffic streams, the transport equipment makes a selection of one of the traffic streams as a reference clock and all the egress traffic streams are then synchronous with the one selected. The clocks from the other traffic streams that are not selected are lost for the system because the system does not use them.
Transport network elements typically receive and aggregate traffic from a plurality of different clients into a single pipe. In this aggregation, the timing transparency is lost. At the time of segregation, the information is not accurately decoded because of the loss of the timing information.
Loss of the timing information has other side effects such as adding latency to the overall system efficiency. Current systems have to incorporate buffering mechanisms to support different clock domains and send signals to the clients when the buffers are full. The clients cannot transmit at their full capacity and therefore have to wait for the transport equipment to be ready before transmitting data.